Project Euler - Problem 20

最新推荐文章于 2025-12-16 13:19:18 发布

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#iterator #iostream #include #string #list #ios

本程序采用C++实现了一个计算100的阶乘（100!）的功能，并将所得大数的每一位数字相加求和。通过迭代增加阶乘的级别，程序能够处理大整数运算中产生的进位问题。

#include <iostream> #include <fstream> #include <string> #include <time.h> #include <list> using namespace std; void Level(list<int> &c , int n) { list<int>::iterator iter = c.begin(); if(*iter > 4) { for(int j = 0;j<181;j++) { c.push_front(0); } } list<int> temp(c); for(int i = 1 ; i<n ; i++) { size_t diff = c.size() - temp.size(); while (diff){ temp.push_back(0); diff--; } for(list<int>::reverse_iterator citer = c.rbegin(), titer = temp.rbegin(); (citer!=c.rend()) && (titer!=temp.rend()); citer++,titer++) { *citer =*citer + *titer; if( *citer > 9) { *citer = *citer%10 ; citer++; *citer = *citer + 1; citer--; } } } //size_t tp = c.size(); //for(list<int>::iterator iter = c.begin();iter!=c.end();iter++) //{ // // if(*iter == 0 ) // tp-- ; // else // return tp; //} } int main() { double start = clock(),end(0); int a[] = {7,2,0}; list<int> l(a,a+3); //size_t alldigits = 11; for(int rank = 7; rank < 101 ; rank++) { Level(l,rank); } //for(list<int>::iterator iter = l.begin();iter!=l.end();iter++) //{ // cout << *iter; //} //cout << "the sum of the digits in the number 100! = " << alldigits << endl; size_t tp = l.size(); int tot = 0; for(list<int>::iterator iter = l.begin();iter!=l.end();iter++) { tot+=*iter; } cout << "the sum of the digits in the number 100! = " << tot << endl; end = clock(); double result = (end - start)/1000; cout.setf(ios::fixed); cout <<endl<< "3.00GHz's run time = " << result << "s."<<endl; return 0; }